docs: def ensure_valid_model_type(specified_type, model_type_list):
      """
      Checks to make sure that `specified_type` is in `model_type_list` and
      raises a helpful error if this is not the case.
  
      Parameters
      ----------
      specified_type : str.
          Denotes the user-specified model type that is to be checked.
      model_type_list : list of strings.
          Contains all of the model types that are acceptable kwarg values.
  
      Returns
      -------
      None.
      """
      if specified_type not in model_type_list:
          msg_1 = "The specified model_type was not valid."
          msg_2 = "Valid model-types are {}".format(model_type_list)
          msg_3 = "The passed model-type was: {}".format(specified_type)
          total_msg = "\n".join([msg_1, msg_2, msg_3])
          raise ValueError(total_msg)
      return None